The concept of lcm is extremely important in number theory and can be easily applied to problems related to work-time, speed-distance, and speed-time. It is mostly used in solving numerical problems such as finding the time taken for two lights to blink together or the ones based on circular tracks where we need to find the time at which the two runners meet. However, before we begin to learn how to find lcm, it is important to get familiar with a few common terms that will help us in calculating lcm. The first step of finding the lcm of two numbers is to have an idea of prime numbers. A prime number is a number that has no other divisor other than the number itself and 1. Numbers like 2,3,5,7,11 and so on are called as prime numbers as they only have 1 and their own number as their factors. However, if we take the number 6, we find that it has 2, 3 and 1 as its factors and is thus, not a prime number.